1. Field of the Invention
The present invention relates generally to a network system, and more particularly to a network information detection apparatus for and method of automatically acquiring network information.
2. Description of the Related Art
To connect a computer to a network, one must set network information such as router IP (Internet Protocol) address and DNS (Domain Name System) IP address to the computer. While such information may be set manually, manual setting requires network knowledge and time and effort must be expended to investigate network information. Erroneous setting of network information may send the entire network into a tailspin.
In the presence of a DHCP (Dynamic Host Configuration Protocol) server, on the other hand, network information can be acquired from the DHCP server. To thus allow automatic acquisition of network information, however, a server must be built that is intended to provide network information.
Japanese Patent Application Unexamined Publication No. 2002-190811 discloses as an example a method of automatically acquiring IP addresses of networked devices. According to the prior art method, when network information cannot be obtained from DHCP server, an effective subnet is determined by analyzing network traffic (see paragraph Nos. 0018 to 0021) and, within the subnet, the default router and the DNS server are detected respectively using an ICMP (Internet Control Message Protocol) router selection message and a SNMP (Simple Network Management Protocol) DNS find request (paragraph Nos. 0025 to 0027).
However, the IP configuration automatic acquisition method as disclosed in the above publication uses the router IP address detection method described in RFC1256 as it is and does not consider speeding up router detection. Besides, some routers do not support ICMP Router Selection, occasionally resulting in routers not being detected by the prior art method.
Similarly, the aforementioned prior art method does not consider speeding up DNS server detection. Besides, some DNS servers do not support SNMP's DNS find request, occasionally resulting in DNS servers not being detected.